Two important methods for producing nonwoven fabrics are the wet laid process and the dry laid process. Both of these methods have their advantages, for example, generally the wet laid process runs at faster speeds, uses cheaper raw materials and is more economical. On the other hand, the dry laid process generally produces a bulkier, more absorbent and softer product. The wet laid process uses a short fiber such as wood pulp fiber which is carried in water, placed on a paper-making type machine and the water removed. The removal of the water from the wood pulp fiber may cause what is termed "hydration bonding" to some degree and produces a stiffer, more paper-like product. The use of water in the process reduces the bulk or the thickness of the product being produced. The wet laid process may be modified by the use of various types of fibers in combinations and the addition of various binder or filler materials.
The dry laid process does not use water and produces a bulkier product. Generally longer fibers are used, the speeds are lower and the dry laid process is usually a more expensive process than the wet laid process.
In recent years a number of techniques have been developed for the dry formation of fabrics from wood pulp fibers which can be run at high speeds. These dry processes overcome some of the disadvantages of the prior dry processes in that more economical raw materials can be used and bulk can still be obtained in the product as water is not used. The dry pulp forming processes, however, unless considerable amounts of binder are used, generally produce weak, but highly absorbent materials. These materials are usually laminated to other materials, but because of their lack of strength may be difficult to handle and convert, that is, cut in shapes, folded, etc.